The purpose of this project is to improve workplace safety and health through research aimed at developing a cost-effective claims-based injury and illness surveillance system which has broad applicability. In this proposal, we will use a database and prospective record linking system developed through our currently funded NIOSH project Analysis of Capitated Payment in Workers' Compensation to create a workplace surveillance program. In Specific Aim I, we will develop the procedures and protocols to transform Workers' Compensation Claims data into a surveillance system for work-related injuries and illnesses. Reports which track workplace injuries and illness events by department will be generated and provided to the employer. In Specific Aim II, we will determine the degree to which the claims-based surveillance system under-reports workplace injuries and illnesses. Workers' compensation claims databases generally include detailed information only on injuries sufficiently severe to require medical treatment. Occupational injury and illness rates and characteristics identified through the surveillance system will be compared with a more comprehensive Employee Injury Report used by the City, to assess the magnitude of under-reporting by the claims-based system. In Specific Aim III we will extend the use of claims-based data to develop and test methods to identify patterns which predict precursor events that could be addressed through primary prevention actions. We will apply time series models on medical claims data collected under this study to explore the issue of identifying important indicators of injury events usable by employers to inform them of changes in workplace safety. In Specific Aim IV, we will develop employer guidelines for using their workers' compensation medical claims databases for surveillance activities. This will result in an explicit product to guide employers in translating their workers' compensation claims data in to a feasible, low-cost and functional surveillance program. This proposal addresses the National Occupational Research Agenda (NORA) priority research area of Surveillance Research Methods and responds to the NIOSH RFA OH-99-0-002 by addressing the need for "Methods to adapt the use of insurance industry data ... to promote the early recognition, reporting, and prevention of workplace illness and injury."